A stroke is caused by the abrupt loss of a nerve function attributable to the interruption of cerebral perfusion resulting from the occlusion or rupture of a blood vessel, is a principal cause of physical disabilities and deaths, and has a serious influence on the health of the elderly persons and middle-aged persons. Strokes are basically classified into a cerebral infarction and a cerebral hemorrhage. In particular, a cerebral infarction has been experienced by about 80% of the total stroke patients, and is known as a significantly serious disease that threatens the survival of humans.
When rapid diagnosis and treatment are not performed in the early stage of the occurrence of a lesion, a stroke is accompanied by serious aftereffects, such as hemiplegia, sensation, language and vision disorders, dementia, etc. In order to minimize such secondary damage, it is extremely important to detect the occlusion or rupture of a blood vessel in its early stage.
Computer tomography (CT) and magnetic resonance imaging (MRI) are used to diagnose a stroke. Meanwhile, magnetic resonance angiography (MRA), computed tomography angiography (CTA), etc. using a contrast agent are used to focus on a cerebral blood vessel where a stroke occurs.
Functional MRI (f-MRI) is used to acquire functional images of a cerebral blood vessel and a cerebral region. A cerebral image analysis technique using f-MRI is disclosed in U.S. Patent Application Publication No. US 2017/0128036 entitled “Method and Device for Functional Imaging of the Brain.” This prior art proposes a method of extracting a functional cerebral region from a cerebral image by using a cerebral vascular atlas.
A medical image processing technology for analyzing a cerebral blood flow disorder is disclosed in U.S. Patent Application Publication No. US 2016/0224744 entitled “Systems and Methods for Embolism Prediction using Embolus Source and Destination Probabilities.” This prior art proposes a model which calculates pressure applied to a narrowed cerebral blood vessel by applying fluid mechanics to the cerebral blood vessel and then predicts the possibility of a blood flow disorder.
Another cause for a stroke or cerebral infarction is the occlusion of a blood vessel which is caused by a cerebral thrombosis. A cerebral thrombosis is a cause for cerebral arteriosclerosis, etc., and refers to a phenomenon in which thrombi are accumulated in a stenosed portion of a cerebral blood vessel and occlude the cerebral blood vessel. A cerebral thrombosis is distinctive from a cerebral embolism in which thrombi generated in another organ, such as the valves of the heart, or the like, move to a cerebral blood vessel along with a blood flow and occlude the cerebral blood vessel. In CT and MRI images, etc., it is difficult to distinguish a cerebral thrombosis from adjacent tissues. Meanwhile, although a blood vessel region can be emphasized in CTA and MRA images, a problem remains still in that the emphasis does not directly help to search for the location of a thrombosis.
In other words, the conventional technologies including f-MRI, CT, MRI, CTA, MRA, etc. have their limitations on searching for the location of a cerebral thrombosis. CTA imaging has its limitations in terms of the range of application due to an increase in the exposure of a patient to radioactive rays, the side effect of a contrast agent, etc.